Multiple Evidence for Gold(I)···Silver(I) Interactions in Solution.

[AuAg3(C6F5)(CF3CO 2)3 (CH2PPh3)Jn (2) was prepared by reaction of [Au(C6F5)(CH2PPh3)] (1) and [Ag(CF3CO2)] (1:3). The crystal structures of complexes 1 and 2 were determined by X-ray diffraction, and the latter shows a polymeric 2D arrangement built by Au-Ag, Ag-Ag, and Ag-O contacts. The metallophilic interactions observed in 2 in the solid state seem to be preserved in concentrated THF solutions, as suggested by EXAFS, pulsed-gradient spin-echo NMR, and photophysical studies, which showed that the structural motif [AuAg3(C6F5)(CF3CO2) 3(CH2PPh3)] is maintained under such conditions. Time-dependent DFT calculations agree with the experimental photophysical energies and suggest a metalto-ligand charge-transfer phosphorescence process. Ab initio calculations give an e timated interaction energy of around 60 kJ mol-1 for each Au-Ag interaction. © 2009 Wiley-VCH. Verlag GmbH & Co. KGaA